In response to the need for electronic devices to cope with an increasing volume of information at ever higher speeds, laminated ceramic components installed in electronic devices need to support higher frequencies. An effective way of achieving this is to reduce the stray capacitance of circuit patterns in laminated ceramic components. An insulating material used in laminated ceramic components thus needs to have a low dielectric constant.
In this type of laminated ceramic component, silver, which has high conductivity, is often used for the circuit patterns formed inside, to reduce electric resistance inside the circuit. Therefore, the insulating material with low dielectric constant needs to be sintered and densified at around 900° C., not higher than the melting point of silver.
Commonly-used insulating materials with low dielectric constant that satisfy the above requirements include a borosilicate material to which a filler such as silica, alumina, forsterite, or cordierite is added. Glass ceramic of borosilicate glass mixed with filler is often used for laminated ceramic components supporting high frequencies. In particular, crystalline silica is often used as the filler for adjusting the thermal expansion coefficient in the case of sintering simultaneously with ferrite, which is a magnetic material. This type of glass sintered at low temperature is disclosed, for example, in PTL 1.
However, silver is liable to spread across a wide area in borosilicate glass if conventional borosilicate glass is used as a low-dielectric material for a glass ceramic layer. Silver thus migrates in the laminated ceramic component. This leads to defects, including short-circuiting, that cause reduced reliability.
In particular, spreading of silver is accelerated if the glass ceramic layer and a ferrite magnetic layer are sintered simultaneously. This significantly reduces the reliability of the laminated ceramic component.
[Citation List]
[Patent Literature]
[PTL 1] Japanese Patent Unexamined Publication No. H11-171640